Regularity For Changes Of 15 Biochemical Indicators And 13 Hormones In Serum Of Grazing Lambs In Warm-season

In this study,20 heads of Kazakh lambs had an average weight of 24.71±2.07 kg,which were selected randomly as subject investigated with 4 months of age from Ili Natural Grassland in the North Bank of Turks River.The research surveyed and evaluated the changes of weight,feed intake,serum biochemical indicators and hormone contents from 2008 May 15 to September 23.The results indicated that:The average daily weight gain of lambs from 4 to 8 months of age were 175±34 g,92±36 g,158±46 g and 81±36 g,respectively.It reached two peaks that were 4～5 and 6～7 months of age.and it were significantly higher than other months of age(P＜0.05).From 4 to 8 months of age,respective dry matter intake of 0.65±0.21 kg,1.45±0.32 kg,1.74±0.48 kg,1.95±0.50 kg,2.30±0.45 kg significantly increased (P＜0.01).Hormone contents determination indicated that the highest NPY contents in the whole period appeared in 5 months of age(39.10±2.60 pg·mL^-1),then the lowest NPY contents in 7 months of age(36.87±1.10 pg·mL^-1).No difference was found in CCK,PP,SS,and Cort contents in different ages of grazing lambs, however,the highest contents of CCK,PP,SS,and Cort appeared in 4 months of age(45.19±9.70 pg·mL^-1), 8 months of age(108.53±19 pg·mL^-1),6 months of age(160.34±10 pg·mL^-1) and 4 months of age(22.1±4 ng·mL^-1),respectively.GAS and T contents increased linearly by age,the highest T₄ contents appeared in 5 months of age(78.3±12.7 ng·mL¹) while the lowest appeared in 7 months of age(65.83±13 ng·mL^-1). Regularity for changes of MTL,SEC,GH,INS and T₃ were the same,increased in 4～5 and 6～7 months of age but decreased in 5～6 and 7～8 months of age.Variation of biochemical indicators showed that there was no difference between each months of age in ALP,LDH and GOT contents,and the highest contents appeared in 5 months of age(256.67±42.46 U·L^-1),8 months of age(515.40±36.69 U·L^-1)and 7 months of age(122.70±13 U·L^-1).TP contents in 7 months of age were the highest in the whole period,while the lowest TP contents appeared in 6 months of age(P＜0.05),TP contents in 7 months of age were 5.96%higher than that of 6 months of age.ALB contents in 4 and 5 months of age were significant higher than that of 6,7 and 8 months of age(P＜0.05); GLB contents in 7 months of age were 8.70%higher than that of 6 months of age.For BUN contents,there was no significant difference among 4,5,7 and 8 months of age,nevertheless.BUN contents of 4,5,7,8 months of age were higher than that of 6 months of age by 9.78%,8.82%,11.02%,14.33%,respectively (P＜0.05).GLU contents in 5 and 7 months of age were 3.30±0.23 mmol·L^-1 and 3.26±0.25 mmol·L^-1, respectively.GLU contents in 5 months of age were significant higher than that of 4,6 and 8 months of age (P＜0.05).An increasing tendency with months of age was shown in TC,GPT,LDL-C and HDL-C contents distinctly.No apparent difference was found in TC and GPT contents between adjacent months of age, LDL-C and HDL-C contents in 7 and 8 months of age were higher than that of 4,5 and 6 months of age (P＜0.05).TG contents showed a downtrend,and that of 7 months of age were higher 28.57%than 8 months of age between adjacent months of age(P＜0.05).FFA contents in 8 months of age were higher than that of other months of ages(P＜0.05),and FFA contents in 6 months of age were higher than that of 5 and 7 months of age evidently(P＜0.05).Overall,the peak and stationary periods of daily gain appeared alternately from 4 to 8 months of age, and dry matter intake significantly increased(P＜0.01).The contents of MTL,GH,INS,T₄ and GLU in serum were the highest at 5 months of age,and SEC,T₃,TP,at 7 months of age.